US4208125A - Cloud altitude measuring apparatus - Google Patents

Cloud altitude measuring apparatus Download PDF

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Publication number
US4208125A
US4208125A US05/911,229 US91122978A US4208125A US 4208125 A US4208125 A US 4208125A US 91122978 A US91122978 A US 91122978A US 4208125 A US4208125 A US 4208125A
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signal
measurement
integrators
accumulator
output
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Expired - Lifetime
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US05/911,229
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English (en)
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Bernt Ling
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Qualimetrics Inc
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ASEA AB
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/08—Systems determining position data of a target for measuring distance only
    • G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/95—Lidar systems specially adapted for specific applications for meteorological use
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
    • Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Definitions

  • This invention relates to cloud altitude measuring apparatus, and particularly to such apparatus wherein the range of the measurement is extended.
  • U.S. patent application Ser. No. 771,261, now U.S. Pat. No. 4,121,889, assigned to the same Assignee as the present invention relates to a cloud altitude measuring means by which the height of a cloud is measured in steps of a certain number of meters per step.
  • the signal emitter emits a series of light pulses.
  • the signal receiver includes two integrating devices, each of which is made operative during a time interval occurring at a certain time T 1 and T 2 , respectively, after each emitted light pulse to receive signals during the time interval.
  • the magnitude of the signals corresponds to the magnitude of the received echo signal as well as any noise signals.
  • the integrating device which is intended for measuring the height to the cloud, receives echo signals from the lower of the two levels corresponding respectively to times T 1 , T 2 .
  • the second integrating device which during the measurement receives echo signals from a higher height, is employed for indicating any accompanying noise.
  • the two signals are supplied to a summation device in which the difference, between the sum of the first signals and the sum of the second signals from a series of light pulses, is determined. When this difference exceeds a certain adjustable value, the existence of a cloud is registered. After each measuring series the integrators are set to zero and a new series of light pulses are emitted in a new measuring step.
  • the present invention relates to an altitude measuring device by which the range of the known cloud altitude measuring means can be considerably extended.
  • the integrators and the summation devices are arranged to treat a plurality of consecutive series of signals before the indicating devices are made operative.
  • the range of the cloud altitude measuring means is approximately proportional to ⁇ number of pulses in each integration.
  • the range is proportional to the square root of the signal/noise ratio, but this relation is in turn proportional to the square root of the number of pulses which are integrated during the measurement.
  • the range is thus approximately proportional to ⁇ n.
  • the cloud altitude can be measured if the measurement continues until the integrating device for the cloud echo signals has significantly greater contents than the integrating device for the noise signals.
  • the echo signals from a number of emitted light pulse series are summed up whereafter the integrator is set to zero;
  • measurement takes place step-by-step, but the result is accumulated and is only indicated after a number of measuring steps;
  • the means according to FIG. 3 is a modification of FIG. 2 in that the indication is carried out in steps but each indication comprises a plurality of measuring steps;
  • FIGS. 4a to 4d show signals occurring during integration and evaluation, step-by-step according to a known method
  • FIGS. 5a to 5c show the signals in the case of integration over a plurality of measuring steps.
  • the cloud altitude measuring means comprises signal emitter 1 emitting a series of laser light pulses 2.
  • Signal receiver 3 receives a series of echo signals 4, including any noise, and transforms the light signals into electrical signals.
  • the signals are supplied to one input of two AND gates 5, 6, the outputs of which are each connected to integrator 7, 8.
  • the outputs of integrators 7, 8 are each connected to an input of summation device 9, integrator 7 being connected to the positive input of the summation device and the output of integrator 8 being connected to the negative input of the summation device. This means that the signal on the output of the summation device corresponds to the difference between the contents of the two integrators 7, 8.
  • the functions of the measuring means are controlled from logic circuit 10. From output 11 of logic circuit 10 the emission of light pulse series from signal emitter 1 is controlled with a specified number of light pulses in each series. Control pulses are emitted from output 12 to two time delay circuits 20, 21 which, after a certain time delay T 1 and T 2 , respectively, supply the control pulses to the second input of gates 5 and 6, respectively, so that the gates are opened and the signal from signal receiver 3 is supplied to the corresponding integrator 7 or 8, respectively. Since the same control pulse from logic circuit 10 is supplied to both gates they are open for an equally long period t each time. However, T 1 ⁇ T 2 , which means that gate 5 opens first and admits echo signals from a lower level than does gate 6.
  • Time t is a time interval, and the difference between T 1 and T 2 must be greater than time interval t. Thus, both integrators 7, 8 must not receive signals simultaneously.
  • Times T 1 and T 2 correspond to the time required for a light pulse to travel from signal emitter 1 to a point of reflection and back to signal receiver 3. The distance corresponding to half of T 1 is chosen as the measuring distance, so when integrator 7 receives an echo signal from a cloud the existence of a cloud at this altitude is detected.
  • the stepping is preferably carried out from a lower towards a higher height. This means that if a cloud is present in the path of the emitted light beam, integrator 8 will receive the cloud echo signal first, but since the output signal of this integrator is supplied to the negative input of the summation device it does not provide any positive output signal therefrom.
  • times T 1 and T 2 increase by an amount which is commensurate to twice the value of the step length, and when the measuring distance has increased so that T 1 corresponds to the cloud height, the echo signals appear at integrator 7, and the summation device has a positive additional charge for each measuring pulse. In this situation integrator 8 receives echo signals from a point inside or beyond the cloud.
  • logic circuit 10 delivers a pulse to time delay circuit 23 which, after time T 4 , delivers a control pulse to level sensing signal evaluating device 30, in which the contents of summation device 9 are evaluated with regard to a value set in the level device, the echo signals received during the measurement thus being evaluated. If the threshold level set in device 30 exceeds the measured value, an output signal 31 is emitted, which indicates the existence of a cloud. Time T 4 is set such that all the light pulse series in a measurement operation can be emitted and the corresponding echo signals be processed in integrators 7, 8 and summation circuit 9.
  • integrators 7, 8 are reset to zero by a control pulse from time delay circuit 22. This control pulse is delayed the time T 3 from the start of the measurement. For the two last-mentioned control pulses, T 3 >T 4 .
  • T 3 >T 4 .
  • the measuring means according to FIG. 2 differs from that described above substantially only by somewhat different signal processing.
  • the signal stored in summation device 9 during a measurement series is supplied to A/D convertor 32, the digital output signal of which is supplied to accumulator 33 by means of a control pulse from timing circuit 25.
  • integrators 7, 8 are reset to zero by means of a control pulse from timing circuit 24, whereafter a new measurement series is emitted.
  • time T 6 for the control pulse to the accumulator is prior to time T 5 for the control pulse which resets the integrators to zero.
  • Accumulator 33 is thus supplied with a certain signal for each emitted series of measurement pulses during the measurement.
  • the input of shift register 34 is connected to the output of A/D convertor 32.
  • Accumulator 35 has its plus input connected to the input of the shift register and its minus input connected to the output of the shift register. Shift register 34 is controlled from control circuit 28.
  • the contents of summation device 9 are transferred via A/D convertor 32 to shift register 34 as well as to the plus input of accumulator 35.
  • shift register 34 is full, each infeed of a number to the input thereof is preceded by an outfeed of a number therefrom to the minus input of accumulator 35.
  • the contents of accumulator 35 correspond to the difference between the numbers fed into shift register 34 and those fed out from it.
  • FIG. 4a shows a perfect signal without disturbance when measuring a cloud height according to the known method, with evaluation for each measurement step, designated s in the Figure.
  • the amplitude for each measurement step indicates the magnitude of the signal obtained for each measurement step.
  • FIG. 4b shows the signal appearing on the output of integrator 8 and which, according to what has been described previously, corresponds to the noise signal at time T 2 .
  • FIG. 4c shows the signal which appears on the output of integrator 7 during each measuring step and which comprises the measurement signal plus noise appearing at time T 1 .
  • FIG. 4a shows a perfect signal without disturbance when measuring a cloud height according to the known method, with evaluation for each measurement step, designated s in the Figure.
  • the amplitude for each measurement step indicates the magnitude of the signal obtained for each measurement step.
  • FIG. 4b shows the signal appearing on the output of integrator 8 and which, according to what has been described previously, corresponds to the noise signal at time T 2 .
  • FIG. 4c shows the signal which appears on the output of integrator
  • FIG. 4d shows the signal which appears on the output of summation device 9 and which, as has been explained previously, is the difference between the signal in FIG. 4c and the signal in FIG. 4b. It is clear from these Figures that when the cloud echo signals are weak the noise signals may be so strong that the cloud echo completely disappears.
  • FIG. 5a shows the noise signal at the output of integrator 8 during a measurement comprising sixteen measurement steps where the measuring distance is changed after each step as shown in FIG. 1.
  • the signals appearing for each individual measurement step correspond to the signals in FIG. 4b.
  • FIG. 5b shows the integrated sum of the echo signal plus noise on the output of integrator 7, the individual measurement values being the same as in FIG. 4c.
  • FIG. 5c shows the total integrated signal which appears on the output of summation device 9.
  • the dash-lined curve in FIG. 5c shows the perfect echo signal according to FIG. 4a for a long integration during sixteen measurement steps. It is clear from FIG. 5c that the two curves agree with each other relatively well, and also that the signal received during integration over a plurality of consecutive measurement steps is considerably stronger and more clear than the signal in FIG. 4d during the stepwise integration and evaluation.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Electromagnetism (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Optical Radar Systems And Details Thereof (AREA)
  • Radar Systems Or Details Thereof (AREA)
US05/911,229 1977-06-03 1978-05-31 Cloud altitude measuring apparatus Expired - Lifetime US4208125A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE7706529 1977-06-03
SE7706529A SE417755B (sv) 1977-06-03 1977-06-03 Anordning for metning av molnhojd

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US4208125A true US4208125A (en) 1980-06-17

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JP (1) JPS543584A ( )
DE (1) DE2822323A1 ( )
FR (1) FR2393321A1 ( )
GB (1) GB1598860A ( )
SE (1) SE417755B ( )

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4643564A (en) * 1982-10-15 1987-02-17 Asea Aktiebolag Cloud height measuring means
US4722599A (en) * 1984-12-27 1988-02-02 Frank Fruengel Device for measuring cloud height
US4979816A (en) * 1987-06-22 1990-12-25 White Steven J Range sensing system
WO2005006016A1 (en) * 2003-07-10 2005-01-20 Eosystem Co., Ltd. Laser rangefinder and method thereof
EP2159603A1 (de) * 2008-09-01 2010-03-03 Sick Ag Objektfeststellungsverfahren und Objektfeststellungssensor
US20120013503A1 (en) * 2009-01-29 2012-01-19 Stefan Heilmann Method for detecting precipitaton using a radar locating device for motor vehicles
RU2569921C1 (ru) * 2014-08-19 2015-12-10 Федеральное государственное казенное военное образовательное учреждение высшего профессионального образования "Военный учебно-научный центр Военно-воздушных сил "Военно-воздушная академия имени профессора Н.Е. Жуковского и Ю.А. Гагарина" (г. Воронеж) Министерства обороны Российской Федерации Способ светолокационного измерения высоты облачных слоев
US10539668B2 (en) * 2016-02-26 2020-01-21 Sony Corporation Positioning device, communication device, and positioning system for reduction of power consumption

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3151333A1 (de) * 1981-12-24 1983-07-14 Früngel, Frank, Dr.-Ing., 2000 Hamburg Verfahren und vorrichtung zur senkung der betriebskosten und erhoehung der zuverlaessigkeit von meteorologischen messgeraeten, insbesondere wolkenhoehen- und schraegsichteinrichtungen mit halbleiter-lasern
WO1988005922A1 (en) * 1987-02-09 1988-08-11 Wild Heerbrugg Ag Procedure and installation for measuring a distance by processing of a pulsating optical signal
US5978736A (en) * 1992-11-20 1999-11-02 Gec-Marconi Avionics (Holdings) Ltd. Vehicle obstruction detection system

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3741655A (en) * 1970-12-11 1973-06-26 E A As Means for determining the existence of an object within a predetermined range interval
US4121889A (en) * 1976-02-27 1978-10-24 Asea Ab Cloud altitude measuring means
US4134677A (en) * 1976-09-09 1979-01-16 Asea Aktiebolag Cloud altitude measuring apparatus

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2446244A (en) * 1943-05-22 1948-08-03 Rca Corp Pulse-echo system
FR1554630A ( ) * 1967-05-25 1969-01-24
GB1204008A (en) * 1968-03-06 1970-09-03 British Aircraft Corp Ltd Improvements relating to range finders
GB1325069A (en) * 1970-12-10 1973-08-01 British Aircraft Corp Ltd Rangefinders
US3899250A (en) * 1974-02-04 1975-08-12 Ball Brothers Res Corp Active-gated television automatic range sweep technique

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3741655A (en) * 1970-12-11 1973-06-26 E A As Means for determining the existence of an object within a predetermined range interval
US4121889A (en) * 1976-02-27 1978-10-24 Asea Ab Cloud altitude measuring means
US4134677A (en) * 1976-09-09 1979-01-16 Asea Aktiebolag Cloud altitude measuring apparatus

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4643564A (en) * 1982-10-15 1987-02-17 Asea Aktiebolag Cloud height measuring means
US4722599A (en) * 1984-12-27 1988-02-02 Frank Fruengel Device for measuring cloud height
US4979816A (en) * 1987-06-22 1990-12-25 White Steven J Range sensing system
WO2005006016A1 (en) * 2003-07-10 2005-01-20 Eosystem Co., Ltd. Laser rangefinder and method thereof
US20070255525A1 (en) * 2003-07-10 2007-11-01 Seok-Hwan Lee Laser Rangefinder and Method Thereof
US7499829B2 (en) 2003-07-10 2009-03-03 A&D Engineering Co., Ltd Laser rangefinder and method thereof
EP2159603A1 (de) * 2008-09-01 2010-03-03 Sick Ag Objektfeststellungsverfahren und Objektfeststellungssensor
US20120013503A1 (en) * 2009-01-29 2012-01-19 Stefan Heilmann Method for detecting precipitaton using a radar locating device for motor vehicles
US8581774B2 (en) * 2009-01-29 2013-11-12 Robert Bosch Gmbh Method for detecting precipitation using a radar locating device for motor vehicles
RU2569921C1 (ru) * 2014-08-19 2015-12-10 Федеральное государственное казенное военное образовательное учреждение высшего профессионального образования "Военный учебно-научный центр Военно-воздушных сил "Военно-воздушная академия имени профессора Н.Е. Жуковского и Ю.А. Гагарина" (г. Воронеж) Министерства обороны Российской Федерации Способ светолокационного измерения высоты облачных слоев
US10539668B2 (en) * 2016-02-26 2020-01-21 Sony Corporation Positioning device, communication device, and positioning system for reduction of power consumption

Also Published As

Publication number Publication date
GB1598860A (en) 1981-09-23
DE2822323A1 (de) 1978-12-07
JPS543584A (en) 1979-01-11
FR2393321B1 ( ) 1984-02-17
SE417755B (sv) 1981-04-06
FR2393321A1 (fr) 1978-12-29
SE7706529L (sv) 1978-12-04

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Owner name: QUALIMETRICS, INC., CALIFORNIA

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